Field of the Invention
The present invention relates to a coil component and, more particularly, to a coil component obtained by embedding a coil conductor in an element body made of a magnetic material.
Description of Related Art
There is widely known a coil component obtained by embedding a coil conductor in an element body made of a magnetic material. In a coil component of this type, an element body is made of a magnetic material, so that most of the magnetic flux generated by making current flow in a coil conductor can be confined inside the element body. However, a part of the magnetic flux leaks outside the element body, which may degrade magnetic characteristics or may adversely affect other electronic components adjacent to the coil component.
To cope with such a problem, Japanese Patent Application Laid-open No. 2013-045848 and Japanese Utility Model Application Laid-open No. H02-067609 disclose a coil component in which a magnetic film is formed on the surface of the element body. In the coil component described in the above publications, a magnetic film is formed on the upper and lower surfaces perpendicular to the coil axis.
However, in the coil component described in the above publications, a large eddy current is generated in the magnetic film with a change in the magnetic flux, resulting in a large eddy current loss. Further, in this coil component, each of the upper and lower surfaces having a high magnetic flux density is covered with a single magnetic film, so that the magnetic film is easily magnetically saturated. Furthermore, in this coil component, spread of the magnetic flux in the side surface direction of the coil component is not sufficiently suppressed, so that when the coil component is mounted on a printed circuit board in a high density, other electronic components adjacent thereto may be affected by leakage magnetic flux.